1. Field of the Invention
The following description relates to a codebook used in a multiple input multiple output (MIMO) communication system, and more particularly, to a codebook used for a transmitter and a receiver when a transmitter of a MIMO communication system includes eight transmit antennas.
2. Description of the Related Art
In a multiple input multiple output (MIMO) communication system, a transmitter and a receiver may use a codebook to share channel information. The channel information may include channel direction information and channel quality information.
The codebook may include a plurality of codewords. The receiver may select a single codeword from the plurality of codewords, and may feed back, to the transmitter, a precoding matrix indicator indicating an index of the selected codeword. The precoding matrix indicator may be an example of channel direction information.
The transmitter may identify the codeword selected by the receiver, based on the precoding matrix indicator, and may generate or determine a precoding matrix based on the selected codeword. The transmitter may precode data based on the precoding matrix, and may transmit the precoded data via a plurality of transmit antennas. The number of transmit antennas may be variously determined, for example, two, four, and eight.